The invention is directed to the field of data storage operations in data processing systems.
It is known to employ a technique referred to as “multipathing” in host computers performing storage operations to a storage system. When multiple distinct paths to a given storage volume are available to a host, the host selects from among the available paths for different storage commands being directed to the volume. Path selection is done to enhance performance by making full utilization of all paths and thereby achieving high utilization of storage resources and lower average latencies of storage operations. Thus paths may be selected based on an adaptive load balancing policy. Path selection may also be used to improve system availability. For example, in the event that a desired path becomes unavailable, path selection may automatically select an alternative path.
In some systems, multipathing functionality is provided by a driver that processes storage commands directed to an external storage system to which the host computer is connected. An example of such a multipathing driver is a driver sold under the name PowerPath® by EMC Corporation.